The United States has called for the "immediate release" of Merrill Newman, an 85-year-old Californian detained in North Korea since last month.

"Given Mr Newman's advanced age and health conditions, we urge the DPRK to release Mr Newman so he may return home and reunite with his family," National Security Council spokeswoman Caitlin Hayden said.

North Korea arrested Mr Newman for "hostile acts" against the state, accusing him of being "a criminal" involved in the killing of civilians during the 1950-53 Korean War.

Mr Newman "masterminded espionage and subversive activities against the DPRK and in this course he was involved in killings of service personnel of the Korean People's Army and innocent civilians," the North's official KCNA news agency said.

DPRK is short for the North's official name, the Democratic People's Republic of Korea.

"He admitted all his crimes and made an apology for them," the Korean news agency said.

In a separate dispatch, KCNA carried what it said was a statement of apology by Mr Newman, made after being detained.

"During the Korean War, I have been guilty of a long list of indelible crimes against DPRK government and Korean people," the statement said.

Mr Newman served as an infantry officer in the Korean War.

He visiting North Korea as a tourist, and was arrested after officials took him off an Air Koryo plane that was scheduled to leave the country on October 26.

Family pleads for release, detainment is "misunderstanding"

Mr Newman is a retiree from Palo Alto in California, and the US State Department has refused to provide any details of the detention.

On Monday, his wife Lee Newman and son Jeff Newman made an impassioned plea to Pyongyang to release Mr Newman.

"We ask respectfully for them to release him and let him come home," Mrs Newman said.

Jeff Newman added the family wanted "nothing more than to have this misunderstanding put behind [them]", appealing for his father to be freed "on a humanitarian basis."

At the time, Swedish diplomats who act as intermediaries between the United States and North Korea had not been able to contact Mr Newman.

Pyongyang has been holding another US citizen and a Christian missionary of Korean decent, arrested last year and sentenced in May to 15 years of hard labour on charges of committing hostile acts against the state.

North Korea is technically still at war with the South and the United States because a truce, not a peace treaty, was signed to end the Korean conflict.

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